Script entry point logging functions

For script based entry points, functions, or wrappers, can call the halog command for message logging purposes. While the halog command can be called directly within the script to log messages, the following entry point logging functions are easier to use and less error-prone:

VCSAG_SET_ENVS - sets and exports entry point environment variables

VCSAG_LOG_MSG - passes normal agent message strings and parameters to the halog utility

VCSAG_LOGDBG_MSG - passes debug message strings and parameters to the halog utility